While reversible pump assemblies are known for alternately supplying washer fluid to the front and back automotive windows, such prior devices included for example, a switching arrangement wherein a flexible membrane is clamped at its peripheral edge so as to be able to flex in either of opposite directions to seat against and seal off oppositely disposed input conduits. Such is the arrangement shown and described in Biancio U.S. Pat. Nos. 4,600,361. Greene 3,485,258 and Felberg 2,992,652 both teach the use of flexible diaphragms clamped at their peripheral edges. In other embodiments, Felberg includes spring loaded plungers extending in opposite directions from the diaphragm, and ball-like protrusions formed on opposite sides of the central portion of the diaphragm.
Other prior switching arrangements have included a spherical ball which is alternately shifted from being seated against one of two axially aligned openings to being seated against the other opening. For example, see Samiet U.S. Pat. Nos. 3,168,898 and Haight et al 2,778,316. Pietryk U.S. Pat. No. 4,679,983 discloses a reversible window washer unit wherein an impeller is secured to a shaft, while a sleeve-like element with two radially outwardly projecting stops is mounted by means of a slipping clutch on the shaft. The stops alternately abut against a projection intermediate two outlet ports in response to the reversed rotation of an impeller to alternately open and close the two ports.
In Gardner U.S. Pat. No. 3,038,487 there is illustrated and described a shuttle valve including a slidably mounted aluminum valve member having resilient seals mounting on the ends thereof, which serves to open and close oppositely disposed inlet ports to alternately feed fluid therefrom to a single outlet port.
Warihashi U.S. Pat. No. 4,331,295 advocates the use of two pairs of pivotally mounted check valves which respectively alternately respond to the reversing directions of an intermediate member.